This disclosure relates to a balancing system and method for adjusting the location of weights to correct for an imbalance on a propeller rotor.
Propeller rotors typically include a plurality of propeller blades which can be driven as a unit about a central axis. The blades have airfoils and roots which are mounted within a hub structure. Propeller rotors are subject to vibration and imbalance. Balance weights may be added to the rotor to correct the imbalance.
Traditionally, aircraft propellers are balanced by the addition of one or more balance weights to the rim of a circular partition of the propeller rotor known as a bulkhead. The angular location and mass of the balance weight is typically determined by the measurement of the vibratory response of an engine, reduction gearbox and propeller system to the application of trial balance weights. The vibration measurements are typically made by recording an electrical response of an accelerometer or similar device mounted on a stationary structure in close proximity to the plane of the propeller. Recording equipment may or may not be permanently installed on the aircraft.
This is a time consuming and inefficient method because it requires test runs and/or test flights where measurements are taken, followed by engine shutdowns where weights are added, removed, or relocated. Furthermore, only one balance solution may be installed for any given flight. Since propeller-induced unbalance typically varies with flight conditions, the present system is not optimal.